PURPOSE: To enable the easy and rapid removal of the display body from the long-sized supporting member, etc., and to assure the reliability of mounting of a display body to a long-sized supporting member as well.

CONSTITUTION: The display body 2 having a display part 40 and a shielding body 9 are arrayed and mounted in the posture of closing an aperture 47a to the long-sized supporting member 47 formed to a bag shape having the aperture 47a in a part of a cross sectional shape. The display body 2 and the shielding body 9 are respectively provided with pieces 3 or 9a to be detained which are elastically engaged with a detaining part 47b or 47c provided on the long-sized supporting member 47 in the posture of projecting in a cantilever form toward the rear side. The detaining part 47b for the piece 3 to be detained on the display body 2 side is so constituted that its engaging force is larger than the engaging force of the detaining piece 47c for the piece 9a to be detained on the shielding body 9 side. The piece 3 to be detained of the display body 2 is provided with an extension part 3a for detaching operation extended from the engaging point for the detaining part 47b.